Polymeric trays and containers have been used by consumers for a variety of purposes such as, for example, holding food items. One commonly used polymer for creating such trays or containers (each hereinafter referred to as a part) is an alkenyl aromatic polymer (e.g., polystyrene). One process of forming the part is to thermoform the part from a web of polymeric material. After the part has been formed in the web of polymeric material, the finished part must be trimmed from the web of material.
Generally, there are two methods of trimming the tray or container from the web of polymeric material: (a) a matching punch and die assembly; and (b) a steel rule trim tool assembly. While matching punch and die assemblies are generally durable, the process creates unwanted trimmings or shavings commonly referred to as “angel hair.” To reduce the presence of angel hairs, manufactures often decrease the lip thickness of the part. However, this reduction in lip thickness adversely affects the strength of the part.
Existing steel rule die assemblies are generally less robust than punch and die assemblies, but are able to create parts with thicker lip edges resulting in a stronger part. One disadvantage of existing steel rule die assemblies is the creation of trim dust. Plastic material created from the process, include trim dust and angel hair, have a tendency to have static charge, which results in such material clinging to the parts and/or the steel rule die assembly. Trim dust is not as long or thick as angel hair, but over time the trim dust tends to build up on the processing equipment. Trim dust and angel hair are referred to herein as “trim scrap.” Trim scrap buildup can result in undesirable buildups of trim scrap on the parts including large visible clumps of trim scrap. These trim-scrap clumps are transferred from the processing equipment to the parts. To remove the trim scrap from the processing equipment at levels desirable to customers results in excessive downtime of the processing operation. It is desirable to have an apparatus for forming and trimming a part that reduces or eliminates trim scrap from the finished part and a process for performing the same.